Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for Vega: 09-20 (100), 09-21 (100), 09-22 (100), 09-23 (100), 09-24 (100) — by astronomy; check the weather when the night is within four days.

2027-09-19astronomy score per night — click a bar for that night2027-10-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-09-19 Sun	86	—	unknown	21:00–01:35 (good, 4.58 h)	87.1° 20:05	8.57	84%	98.1°
2027-09-20 Mon	100	—	unknown	21:00–01:40 (good, 4.67 h)	87.1° 20:00	8.62	76%	103.5°
2027-09-21 Tue	100	—	unknown	20:55–01:45 (good, 4.83 h)	87.1° 20:00	8.67	66%	108.3°
2027-09-22 Wed	100	—	unknown	20:55–01:45 (good, 4.83 h)	87.1° 19:55	8.72	56%	112.3°
2027-09-23 Thu	100	—	unknown	20:55–01:45 (good, 4.83 h)	87.1° 19:50	8.77	44%	115.1°
2027-09-24 Fri	100	—	unknown	20:50–01:40 (good, 4.83 h)	87.1° 19:45	8.82	33%	116.4°
2027-09-25 Sat	100	—	unknown	20:50–01:40 (good, 4.83 h)	87.1° 19:40	8.87	23%	116.0°
2027-09-26 Sun	100	—	unknown	20:45–01:35 (good, 4.83 h)	87.1° 19:40	8.92	14%	113.7°
2027-09-27 Mon	100	—	unknown	20:45–01:35 (good, 4.83 h)	87.1° 19:35	8.97	7%	109.9°
2027-09-28 Tue	100	—	unknown	20:45–01:30 (good, 4.75 h)	87.1° 19:30	9.02	2%	104.8°
2027-09-29 Wed	100	—	unknown	20:40–01:25 (good, 4.75 h)	87.1° 19:25	9.07	0%	98.9°
2027-09-30 Thu	100	—	unknown	20:40–01:20 (good, 4.67 h)	87.1° 19:20	9.12	1%	92.7°
2027-10-01 Fri	100	—	unknown	20:40–01:15 (good, 4.58 h)	87.1° 19:20	9.17	4%	86.4°
2027-10-02 Sat	100	—	unknown	20:35–01:15 (good, 4.67 h)	87.1° 19:15	9.22	10%	80.5°
2027-10-03 Sun	100	—	unknown	20:35–01:10 (good, 4.58 h)	87.1° 19:10	9.26	17%	75.2°
2027-10-04 Mon	100	—	unknown	20:35–01:05 (good, 4.5 h)	87.1° 19:05	9.31	26%	70.6°
2027-10-05 Tue	97	—	unknown	20:30–01:00 (good, 4.5 h)	87.1° 19:00	9.36	35%	67.1°
2027-10-06 Wed	90	—	unknown	20:30–01:00 (good, 4.5 h)	87.1° 19:00	9.4	44%	64.7°
2027-10-07 Thu	80	—	unknown	20:30–00:55 (good, 4.42 h)	87.1° 18:55	9.45	54%	63.5°
2027-10-08 Fri	66	—	unknown	20:25–00:30 (good, 4.08 h)	87.1° 18:50	9.5	63%	63.6°
2027-10-09 Sat	57	—	unknown	20:25–00:05 (good, 3.67 h)	87.1° 18:45	9.54	72%	64.8°
2027-10-10 Sun	51	—	unknown	20:25–22:45 (good, 2.33 h)	87.1° 18:45	9.59	80%	67.2°
2027-10-11 Mon	47	—	unknown	20:20–22:05 (good, 1.75 h)	87.1° 18:40	9.63	87%	70.6°
2027-10-12 Tue	46	—	unknown	20:20–21:50 (good, 1.5 h)	87.1° 18:35	9.68	93%	74.8°
2027-10-13 Wed	47	—	unknown	20:20–21:55 (good, 1.58 h)	87.1° 18:30	9.72	97%	79.8°
2027-10-14 Thu	51	—	unknown	20:15–22:15 (good, 2.0 h)	87.1° 18:25	9.77	99%	85.2°
2027-10-15 Fri	57	—	unknown	20:15–22:45 (good, 2.5 h)	87.1° 18:25	9.81	100%	90.9°
2027-10-16 Sat	64	—	unknown	20:15–23:20 (good, 3.08 h)	87.1° 18:20	9.85	98%	96.7°
2027-10-17 Sun	72	—	unknown	20:10–23:45 (good, 3.58 h)	87.1° 18:15	9.9	94%	102.3°
2027-10-18 Mon	80	—	unknown	20:10–23:50 (good, 3.67 h)	87.1° 18:10	9.94	88%	107.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-09-19&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.